Magnetitteilchen, bestehend aus magnetischen Eisenoxid, Verfahren zur Herstellung und dessen Verwendung

摘要

Magnetic Fe oxide is claimed which: (1) has an Fe content of 45-73 wt.%, a brightness (L*) of 45.0-65.0 CIELAB units and colour values (a*) and (b*) of -0.5 to 1.5 and -1.0 to -7.0 CIELAB units respectively; and which (2) has its triboelectric charge increased by at least 30% on account of the presence of 0.1-5 wt.% of an oxide, hydroxide, oxyhydroxide or easily or difficulty water-soluble salt of Li, Na, K, Mg, Ca, Sr, Ba, Mn or Zn or an organic Zr (IV)-, Ce (IV)- or Sn (IV)-compound. Also claimed is production of the material by mixing the Fe oxide with the additive in solid or liquid form, especially by mixing the additive with an aqueous dispersion of the Fe oxide. Preferably the additive is especially: (i) an oxide or hydroxide of Ca, Mg, Mn or Zn; or (ii) a Zr (IV)-, Ce (IV)- or Sn (IV)-fatty acid ester.